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Cont-roo-ception: Hormone implants bring kangaroos under control

Where have the joeys gone?

National Geographic Creative/Alamy Stock Photo

By Alice Klein

A CONTRACEPTIVE has made the jump from women to kangaroos. A large trial of hormonal implants in roos in south-east Australia has reduced the number of the animals born, removing the need to cull them by shooting.

Australia has twice as many kangaroos as people. When numbers become high locally, more of the animals collide with cars, and they contaminate water supplies and damage grasslands. To control numbers – and supply kangaroo meat – more than 5 million wild kangaroos are culled a year.

But there is increasing opposition to this from animal welfare groups. To see if contraception could be an effective alternative, Michelle Wilson of the University of Melbourne has been giving kangaroos hormone implants usually used by women.

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In 2013, Wilson put levonorgestrel implants under the shoulder blades of three-quarters of the female kangaroos in a 200 hectare area of the Western Plains of Victoria. “There were too many kangaroos so there wasn’t enough food and they were starving and emaciated,” she says.

A follow-up study has now found that, of the 75 females that were implanted, only one has become pregnant since. The reproductive rate of this population is now about a third of what it was in 2012.

“It’s prevented the need for us to go back and do any more shooting,” says Phil Pegler of Parks Victoria.

The contraceptive method costs around $A 250 (£130) per animal, but is better in the long term, says Wilson. “The problem with culling is that the population bounces back afterwards.”

This article appeared in print under the headline “Wild kangaroo numbers cut by cont-roo-ception”